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Registered
Join Date: Jun 2009
Location: Manhattan Beach, California. Factory Delivery-Original owner-Retired engineer
Posts: 5,238
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Auto heat servo unit.
The activation noise on our '86 Auto Heat Control Unit located between the seats has increased over the last few years.
The noise appears to be a "whirring" and "squeal" type noise when the servo is activated to adjust the cabin temperature (0-10). Upon reaching the the appropriate setting(s), the noise(s) are no longer present. The footwell blowers have no anomolies, and provide excellent heat which varies in intensity/temperature depending on rotary switch setting(s). Our use of the Auto Heat is infrequent. I'm aware that the servo opens, and closes the flapper boxes. Are the flapper boxes settings too tight applying excessive strain on the servo? Is the servo motor subject to lubrication, or is it a sealed component? Thanks in advance, and the best of New Years to all. Gerry 
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1986 911 Targa. Per Road and Track magazine: Only in L.A.: In the window of a bar in Hermosa Beach, California. "Happy Hour prices during all car chases." |
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01-02-2010, 05:33 PM
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Registered
Join Date: Oct 2008
Location: Nash County, NC.
Posts: 8,505
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Your shielding of the wire to the flapper boxes is getting plugged with dirt. You need to service them by removing the shield and spraying cleaner through them.
Its also about time to change the nylon connections inside the box between the seats as they get frail and break. there are two, about $2.00 each and a hundred dollars in time, DIY. Bruce |
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01-02-2010, 05:39 PM
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Join Date: Aug 2008
Location: sectors R&N, SE Pa
Posts: 3,117
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Gerry,
Timely post - this is the exactly the situation I apparently have and was attempting to inquire about just a few hours ago. As I have only owned my car for only 2 years, and shut her down early last year for the winter, I have had no basis of reference with which to compare my current symptoms due to limited use, and hence I couldn't tell if the servo actuation was supposed to be that loud/audible or if it was cause for concern. My thanks to you and Bruce as I now know what to do about it as well.
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Dan '87 Targa Carrera 3.2 - Fabspeed Cat Bypass, M&K Muffler, SW Chip Venetian Blue |
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01-02-2010, 06:01 PM
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Join Date: Apr 2005
Location: outta here
Posts: 53,409
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I'll add two things. Disconnect the cables from the valves under the car and make sure the valves operate freely. They tend to rust over time. Then, take a look at the plastic sleeve on each side that houses the cable. Make sure the cable hasn't worn a groove in the sleeve at any point, from the constant back and forth motion. If all is good, clean, re-lube and reassemble all the parts.
JR |
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01-02-2010, 06:20 PM
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Registered
Join Date: Apr 2009
Location: CA
Posts: 684
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I've got a set-up that I removed from my '79SC for sale (cheap) if anyone needs one.
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01-02-2010, 07:47 PM
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Registered
Join Date: Jun 2009
Location: Manhattan Beach, California. Factory Delivery-Original owner-Retired engineer
Posts: 5,238
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Auto Heat issues.
It would appear that due to the infrequent use of our Auto Heat, all we needed
was a bit of Water Displacement 40 on the Baffles. No rust. Excessive load on the servo motor? That little servo motor was certainly "earning" it's keep...... Also, I serviced the footwell blowers. All is well, and quiet. Thanks all for the intuitive and professional posts. Best of New Years to all, Gerry
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1986 911 Targa. Per Road and Track magazine: Only in L.A.: In the window of a bar in Hermosa Beach, California. "Happy Hour prices during all car chases." Last edited by 86 911 Targa; 01-03-2010 at 03:47 PM.. |
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01-03-2010, 03:39 PM
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